Cooperative motion and growing length scales in supercooled confined liquids

TL;DR

This study uses molecular dynamics simulations to explore how confinement near rough and smooth walls affects the relaxation dynamics of supercooled liquids, revealing growing dynamical length scales with decreasing temperature.

Contribution

It introduces a method to extract dynamical length scales from confined supercooled liquids and highlights the challenges in interpreting experimental susceptibility data.

Findings

Relaxation times vary significantly near rough and smooth walls.

Dynamical length scales increase as temperature decreases.

Experimental susceptibility data are difficult to interpret in confined systems.

Abstract

Using molecular dynamics simulations we investigate the relaxation dynamics of a supercooled liquid close to a rough as well as close to a smooth wall. For the former situation the relaxation times increase strongly with decreasing distance from the wall whereas in the second case they strongly decrease. We use this dependence to extract various dynamical length scales and show that they grow with decreasing temperature. By calculating the frequency dependent average susceptibility of such confined systems we show that the experimental interpretation of such data is very difficult.